It has been conventional in the glass fiber forming art to use bushings that have orificed projections to flow streams of molten glass material for attenuation into fibers. By using such orificed projections, the undersurface or bottom wall of such bushings is less likely to flood with molten glass material during an interruption of the fiber forming process. During an interruption of the process, the exiting glass of a tipped bushing will generally form beads at the exit of each tip rather than flood across the bottom wall to form a large mass of glass covering the undersurface of the bushing.
However, by using bushings which include tips or orifice projections, one is physically limited by the walls of the tips to certain maximum orifice densities in the bottom wall. If the tips or projections can be eliminated from the bottom surface of the bushing, the orifices can be packed more closely together, and thus, higher orifice density bushings can be utilized.
The use of tipless bushings, i.e., bushings having a generally flat undersurface, is described in U.S. Pat. No. 3,905,790 and in British Pat. No. 1,498,184.
However, utilization of such high orifice density tipless bushings has been limited because of the difficulty in running such bushings and in restarting such bushings after an interruption. Improved apparatus is desired for the production of glass fibers through tipless bushings.